Re: [PATCH] overcommit symbolic constants

[Andries Brouwer]

On Thu, Sep 30, 2004 at 01:53:12PM +0100, Alan Cox wrote:
> On Iau, 2004-09-30 at 14:41, Andries.Brouwer@xxxxxx wrote:
> > Played a bit with overcommit the past hour.
> > Am not entirely satisfied with the no overcommit mode 2 -
> > programs segfault when the system is close to that boundary.
> 
> Not really a suprise. Very few programs handle stack growth faults.
> Hence the docs comment about mmapping stacks privately for critical
> code.

Most utilities do not expect to be oom-killed, but they do not
expect to be killed by segfault because of stack shortage either.
So avoiding the oom-kill and getting segfaults is no improvement
in my eyes.

A few days ago I remarked that 2 is no good when there is no swap.
OK. So, more modest aim - tighten things only in case there is
plenty of swap. I like to return NULL for malloc(), that is
something a good program tests for. I hate to fail a stack grow.
So, must play a bit more, see whether I can find a mode much
stricter than 0 that is still suitable as a general working
environment for everybody.


Andries


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